Polymerization of butadienes



Patented 8, 1941 UNIT-ED STATES PATENT OFFICE- v 3: BU'IADIENES Knrt-Meisenburg,

Leverkusen I. G.

Welt,

Ingofroh Dennstedt, Cologne-Buclflorst, and

Ewald zancker,

Colcgne-Mulhelm on --the- Rhine-Germany, aasignora'by meane assignments,to .lasco, Incorporated, a corporation of Louisiana No Drawing.Application February 28, 1938; Se-

rial No. 193,060. GermanyMarch 2, 1937 8 Claims. (CLEO-32) The presentinvention relates to a new process of polymerizing butadienes-lfi and tothe new polymerizates which are obtainable thereby.

It is known that the polymerization of butadienes-l.3 easily results intheformation of prod ucts which are insoluble in benzene and resemblevulcanized'rubber rather than the unvulcanized product. In consequencethereof, the working of these products on the roller and theincorporation therewith of'illling materials and the in gredients whichare necessary for effecting vulcanization is connectedswith considerabledifli-. culties. Moreover, themechanical properties of the vulcanizatesobtained from such products are materially impaired when compared withthose.

vulcanizates obtained from benzene soluble polymerizates. In order toavoid these disadvantages it has been proposed to effect the heatpolymerization of butadienes-1.3 in the presence of sulfurv or certainsulfur containing compounds. It is not disputed that certainimprovements are obtained thereby; however, by the use'of theseadditions the disadvantage is involved that the course of I thepolymerization is considerably retarded; moreover, the presence ofsulfur and the said sulfur containing compounds may result in theformation of undesired dimeric by-products.

It is the object of the present invention to do away with thesedisadvantages and to develop a It has been found that organic sulfurcontaining compounds which are soluble in the monomeric substances to'bepolymerized exert a remarkable regulating eflect upon the course of theemulsion polymerization. sulfur containing products are preferred whichcontain at least 2 sulfur atoms .directly connected with each other, i.e. organic disulfldes. Examples for suitable regulators aremalkylxanthogen; di (benzoic acid ester) tetra sulfides, tolyldimlfldeand tolyltrisulflde. In most cases an'amoimt of less than 1% of theseregulators (calculated on the amount of monomeric products) ia'suilcientto exert the desired eifectrin other cases someis properties.

what higher amountsare required. Depending.v

on the amount of the regulators the resulting polymerizates eitherresemble natural rubber orare of a more plastic nature, the yield andsolubility in organic solvents such as benzene being excellentregardless of the amount of such re8lllators. In this respect our newprocess is superior to the hitherto employed heat polymerization in thepresence of sulfur and sulfur containinscom- 10 pounds; since in thelatter case the amount of the'regulators must be carefully controlled ifa good yield is to be combined with a good solubility of thepolymerizates.

The new process can be applied to every polylli merizable butadiene-1.3, the latter term being intended to comprise the unsubstitutedbutadiene as well as the homologues thereof such as isoprene. As amatter of fact, also mixtures of such butadienes with otherpolymerizable compounds such asstyrene o'r acrylic acid nitrile can beemployed. It is to be understood that such sulfur containing'regulatorsare preferred, as have only a weak vulcaniz'ing eifect or no such effectat all.

The following examples illustrate the present invention without,however, restricting. it thereto the'parts being by weight:

' trample 0.5 part of diisopropylxanthogendisulflde aa- 30. solved in 69parts of butadiene are emulsified in 200 parts of a 5% sodium oleatesolution containing 0.3 part of ammonium persulfate. After a severaldays shaking a soluble plastic polymeiizate is obtained in aquantitative yield. sample 2 0.1 part of diisopropylxanthogendisulfldedis- .solved in 52 parts of butadien'e and 22. parts styrene areemulslfiedin 200 parts of a 5% sodi- 49 um oleate solution containing0.3 part of ammonium persuli'ate. After a severaldays shaking at 30 andupon coagulation there is obtained ina nearly quantitative yield an]easily soluble mixed polymerilate which. shows excellent I mechanical,

. tremble 3 I v parts of butadiene. and 25 parts oftmne are'emulsiiiedin.142 parts of water having dissolvedthereinilpartsofaodiumdiiaobutylnaphthalene sulfonate, 02 m or sodium 2 a and 0.375 part of potassiumpersultate. Polymerization is efiected by a 5 to 6 hours shaking at 30.Theiiollowing table shows the yield of soluble polymerizates obtainedunder the influ-' ence of varying amolmts of tolyldisulfide asregulator:

:Ygeld 011mg Amount 0! regula in pelw'cent m we m n polymerizablesubstances figg igi amount We claim:

1. The process which comprises effecting the emulsion polymerization ofbutadiene 1.3 hydrocarbons in the presence of such organicsulfurcontaining compounds as contain at least 2 sulfur atoms directlyconnected with each other and are soluble in the monomeric substances tobe polymerized, said compounds being selected from the .group consistingof dialkylxanthogendisulfides, di(benzoic acid ester) -tetrasulfides,tolyldisulfide and tolyltrisulfide.

2. The process which comprises efiecting the emulsion polymerization ofbutadiene-L3 hydrocarbons in the presence ofdialltylxanthogen'disulfides.

3. The process which comprises effecting t e emulsion polymerization ofbutadiene-L3 hydr carbons in the presence ofdiisobutylxanthogendisulfide.

4. The process which comprises efiecting'the emulsion polymerization ofbutadiene-1.3 hydrocarbons in the presence of di(benzoic acid ester)butadiene-L3 to a conjoint emulsion polymerizav tion with styrene in thepresence of dialkylxanthogendisulfldes.

8. The process which comprises subjecting butadiene 1.3 to'a conjointemulsion polymerization with acrylic acid nitrile in the presence ofsuch organic sulfur-containing compounds as contain at least 2 sulfuratoms directly connected with each other and are soluble in themonomeric substances to be polymerized, said compounds being selectedfrom the group consisting of dialkylxanthogen-disulfides, di(benzoicacid ester) tetrasulfides tolyldisulfide and tolyltrisulflda' KURTMEISENBURG. INGOFROH DENNSTEDFI' EWALD ZAUCKER.

